7 April 2008

Dengue in Brazil

Dengue is endemic in Brazil and outbreaks are frequently reported [1,2]. The Brazilian health authorities have reported a significant increase in the number of cases of dengue and dengue haemorrhagic fever (DHF) in several states since the beginning of January 2008, compared to the same period of 2007 [3]. In Rio de Janeiro State, 32,615 cases of dengue (representing 38% of the total reported in Brazil) and 245 cases of DHF were reported from 1 January to 28 March 2008. During the same period, reports of DHF in Amazonas, Rondonia, Sergipe, Bahia, Rio Grande do Norte, Para, and Rio de Janeiro states have increased compared to 2007 [3]. The circulating serotypes have been confirmed as DEN 2 and DEN 3. Vector control measures are being carried out in both the state and city of Rio de Janeiro; community based interventions are being implemented and increased support for patient management has been arranged.

Dengue is an arthropod-borne virus of the Flaviviridae family. There are four serotypes of dengue virus classified as DEN 1 to 4. The virus is transmitted to man by the bite of an infected Aedes mosquito; A. aegypti is the principle vector, but A. albopictus has also been responsible for transmission of dengue in some countries. Dengue is recognised in more than 100 countries and between 250,000 to 500,000 cases are reported to the World Health Organization annually.

The majority of cases of dengue are sub-clinical or mild. Following an incubation period of five to eight days, a fever develops which lasts from one to five days. Other symptoms include headache, myalgia, and cough. A maculopapular rash typically spreading from the trunk to the limbs and face, develops between three and five days after onset of the illness. Most patients will make a rapid recovery three to four days after onset of the rash.

Dengue can progress to the more serious DHF. This is more common in children and rarely seen in travellers. It is not certain what precipitates such progression, although previous infection with a different serotype of dengue may predispose to DHF on re-infection. During DHF there is a sudden deterioration with diffuse bleeding and shock, leading to organ failure.

There is no specific treatment for dengue or DHF. Supportive care and management of symptoms are the standard. 

Advice for travellers

There is no vaccine available to protect against dengue. Travellers to endemic areas can reduce their risk of infection by the dengue virus by practising mosquito bite avoidance measures. Aedes mosquitoes responsible for transmitting dengue are active during daylight hours. Particular vigilance with bite avoidance should be taken around dawn and dusk.

References

1. Pan American Health Organization (PAHO). Dengue in the Americas, 2007, Emerging and Re-emerging Infectious Diseases, Region of the Americas;4 (8) available at  http://www.paho.org/English/AD/DPC/CD/eid-eer-2007-09-26.htm#bra accessed 7 April, 2008

2. The National Travel Health Network and Centre, Country Information Pages, Brazil: Outbreak Surveillance available at http://www.nathnac.org/countrysearch.aspx?COUNTRYCODE

=BR

3. Pan American Health Organization (PAHO), Dengue in Rio de Janeiro, Brazil, Emerging and Re-emerging Infectious Diseases, Region of the Americas;5 (9) available at http://www.paho.org/English/AD/DPC/CD/eid-eer-2008-03-26.htm accessed 7 April, 2008

Link

NaTHNaC Health Information Sheet on Dengue Fever